The invention relates to a tilt cylinder device for a marine drive unit, such as an outboard engine or the outboard drive portion of an inboard/outboard engine for boats, rafts and other marine vessels positioned so that the stress acting on the tilt cylinder device and its associated parts is decreased.
One form of an outboard drive unit is attached to the hull of a marine vessel by a clamp bracket and an elongated swivel bracket secured to the clamp bracket by a tilt shaft that allows the drive unit to be selectively tilted downwardly into, or upwardly out of, the water. This type of swivel bracket is normally used on vessels having a high transom such as a sail boat.
A lower positioned stop pin, engageable with the swivel bracket, is used for deciding the downward position of the swivel bracket and the trim adjustment. In order to perform satisfactorily the tilt cylinder device should preferably be capable of maintaining the drive unit in a downward position during normal operation so that the drive unit does not swing upwardly due to the thrust of the propeller when the vessel is driven in the reverse direction. The tilt cylinder device should preferably also prevent the drive unit from being swung upwardly by the resistance of the water when the vessel suddenly decelerates or stops. In order to minimize damage to the drive unit, however, the tilt cylinder device preferably should allow the drive unit to swing upwardly in the event of a collision with a submerged object.
Previous tilt cylinder devices typically attempt to perform some or all of the above functions. Such tilt cylinder devices are generally connected at one end to the swivel bracket and at the other end to the clamp bracket at a position between the axis about which the swivel bracket rotates and the stop pin for the purpose of reducing the size of the clamp bracket. However, such tilt cylinder device arrangements have been unsuccessful in reducing the stress which acts on the tilt cylinder device and its associated support members during collision.